It is presently normal for control valves for fluid-powered actuators with cylinders to be placed at some distance from them, for example in a control console, the ports of the control valve being joined up with the ports of the actuator cylinder by long fluid power pipes or leads.
It is, more specially, in the case of compressed air-powered fluid actuator cylinders disadvantageous because such long pipes are responsible for a slow response of the cylinder; furthermore, if control valves are placed in consoles or at some other position at some distance from the cylinder of the actuator, it is hard to make changes in the system.